With the development of information-oriented society, demand for display devices is increasing. To meet such demands, various types of display devices such as an LCD (Liquid Crystal Display), PDP (Plasma Display Panel), ELD (Electro luminescent Display) and VFD (Vacuum Fluorescent Display) have recently been researched and used.
From among such display devices, display devices using an organic light emitting diode (OLED) can be implemented as ultra-thin displays since the display devices have excellent luminance and viewing angle characteristics and do not require a backlight unit, compared to LCDs.